Should You Take a Multivitamin?



Since the early 1940s, when multivitamin/mineral supplements first became available, Americans have popped countless such pills in hopes of “nutritional insurance” and making up for any dietary shortfalls. Today, more than one-third of all Americans take a multivitamin, and multivitamins alone account for more than 40% of all vitamin and mineral supplement sales—an estimated $5.4 billion annually. Yet the scientific evidence for the benefits of multivitamins is mixed at best, with large recent studies reporting no association between usage and better cardiovascular or cognitive health and only modest cancer protection.

What do the experts say? Tufts’ Julie Flaherty sat down with four of the university’s nutrition scientists (see box) for a roundtable discussion about the science of multivitamins and to answer a simple question: Should healthy adults take them?

Flaherty: I am a fairly healthy adult, and I think I eat a slightly better-than-average diet. My doctor says I should take a multivitamin—she recommends it for all women my age. Should I take one?

Jeffrey Blumberg: There is no harm in taking a multivitamin and, importantly, doing so will help fill in the substantial gaps that are consistently apparent in national surveys of intake. Over two-thirds of Americans fail to meet the Estimated Average Requirement (EAR) for vitamins D, E, and K and for the minerals magnesium and potassium; about 40% fall short of the EAR for vitamins A and C. In large part, these nutrient inadequacies are due to common dietary patterns that continue to fall short of the recommended consumption of fruits, vegetables and whole grains. So, while we try get people to change their eating behavior, taking a multivitamin seems a prudent action.

Alice H. Lichtenstein: Your physician’s recommendation is not consistent with current clinical guidelines. There was a very extensive systematic review sponsored by the federal government that was done by the Johns Hopkins Evidence-Based Practice Center that showed no benefit to the general population from taking a multivitamin. It may be useful in certain select groups, but we know that in the US, those individuals who need a multivitamin most—those who are nutrient-insufficient—are less likely to use supplements. We’re not even sure whether falling a little bit below the Recommended Dietary Allowances (RDAs) will cause a problem because, in general, clinical manifestations of nutrient deficiencies are rare.

One of the problems is that when you put an emphasis on something like whether people should take a multivitamin, you shift the focus off what is really important: that they are eating too many calories, too much saturated fat and trans fat, too much sodium, not enough fiber, and they are not exercising enough. There is no quick fix. You can’t just pop a pill and make everything better.

Blumberg: I agree. If you want to take a multivitamin because you love to eat at fast-food restaurants five times a week, and you hate fruit and vegetables and you think you can compensate for that, my answer is no, you can’t. Multivitamins are supplements, not substitutes for a healthy diet.

And I agree that the people who need a multivitamin most are the ones who aren’t taking them. Who is taking a multivitamin? The more affluent, the more highly educated, the people who are actually eating better diets, who exercise, don’t smoke. The people who really need to be listening to their doctor’s advice to take a multivitamin are not.

But I don’t agree with the converse: that people who need them the least don’t need them at all, because they are not meeting their RDAs either. Maybe some of the RDAs are not perfect, but they are a goal that reflects the current scientific consensus, and we know that most people aren’t meeting it.

Johanna Dwyer: Speaking for myself, I don’t think that a multivitamin is going to cause any particular good, nor do I think it is going to cause any particular harm. It’s a personal choice. It’s like whether people should be avoiding every animal food or everything that has added sugar. A lot of these blanket statements about absolutely consuming or not consuming foods or multivitamins are oversimplified, inconsequential, yuppie-related food faddism. Some examples where a multivitamin-mineral dietary supplement at RDA or DV levels may be useful are with the very old and frail who eat very little, and with chronically ill children whose appetite fluctuates widely. Some examples where they are not are people who are taking three or four pills a day in the hope that their sports performance will improve. They’d be better off training more.

Flaherty: When I asked a few people why they take multivitamins, they said things like, “I’m a little anemic, so I need the iron,” or “That’s how I get my vitamin D.” It seems to be one-stop shopping for a variety of concerns.

Joel Mason: I think the mindless approach that many Americans (and, for that matter, many American physicians) take—that it might help, and it can’t hurt—is not a very rational perspective, nor is it very appropriate. It simply ignores the fact that taking supplements should be tailored to each individual’s particular needs. For instance, a young woman might not be getting enough vitamin D and calcium to support her bone health. A multivitamin might not be the right approach since most multivitamins—even if they include minerals as well—have a trivial amount of calcium and often inadequate amounts of vitamin D to optimize bone health. Nevertheless, this young woman and her physician might be dissuaded from thinking about the issue further because they have been lulled into complacency by the false reassurance that a multivitamin provides. If you really think carefully about what you as an individual need, most often you are going to end up with a more intelligent strategy.

Lichtenstein: If your physician finds that you need more calcium, I would ask, have you tried non-fat Greek yogurt? Do you think there is a way of increasing your dairy intake? There are so many food-based ways of getting your nutrients. And a benefit is other nutrients come along with the one of concern when you take the food-based approach.

Dwyer: Years ago I was studying vegetarians, and some of them told me they took a vitamin supplement because they weren’t getting enough calcium and iron. If you looked at the vitamins they were taking, they were indeed vitamins, but the calcium and iron they needed were minerals.

Indiscriminate vitamin use is sort of like the use of holy water in the Middle Ages: People thought if you sprinkled it on things, it would ward off all evil. Some people really believe that. If you look at their reasons, they are not more sophisticated than beliefs in the Middle Ages. And I worry about self-diagnosis of what could be concerning health conditions that are developing. On the other hand, there are some supplements that I think are worth taking such as vitamin D and calcium in postmenopausal women. I take them, and I am sure many others do as well.


Flaherty: Let’s talk about the risks. What about the 2011 Iowa Women’s Health Study, the observational study that found there was an increased risk of death in women who took multivitamins?

Dwyer: To say that multivitamins are causing mortality—I really believe that is a big stretch, and I don’t think that particular paper is in line with the rest of the literature. Most of the studies that say things like that are not controlling for the confounders, such as smoking, obesity, preexisting illness, etcetera. Sadly, you can’t control for all of the confounders in an observational study.

It’s extremely expensive to study multivitamins well in large randomized clinical trials that last for many years, especially with hard end points such as mortality or heart attacks. There have been several very good, randomized studies that did not show any adverse effects from multivitamins. And a recent paper we did, published in the Journal of Nutrition, showed reduced mortality from cardiovascular disease was significantly associated with taking multivitamin-mineral supplements for three years or longer for healthy US women but not for men. No significant associations were found for use of multivitamins without minerals and cardiovascular disease mortality. However, the findings need to be interpreted with caution because it was an observational study of people in NHANES [a national survey], and many other things could have been involved as confounders. So what is needed is more good research.

Blumberg: There are now several meta-analyses of multivitamins and mortality, and they show no benefit to increasing longevity, but no harm either. The Physicians Health Study II tested a complete multivitamin in 15,000 men and reported a modest but statistically significant reduction in the incidence of total cancer. I don’t wish to overstate the benefit found here, but this was a large, long-term and well-controlled study. Not surprisingly, many have pointed out the complexities and limitations associated with this and similar studies. Yet if investing tens of millions of dollars in a randomized clinical trial like this—the purported “gold standard” for medicine—is still insufficient to provide convincing evidence of benefit, then we need to find new and practical approaches to do so.

Image © Thinkstock

Lichtenstein: In talking about potential harm, the other thing we have to remember is that a tremendous amount of the foods and beverages we consume is fortified. If you are consuming a bowl of breakfast cereal that has 100% of the RDA, if you are getting orange juice that has calcium and vitamin D added to it, or a powdered beverage mix that has vitamin C, you already may be getting the equivalent of a multivitamin pill.

I think we are just beginning to learn about the effects of overconsumption of nutrients. We really don’t know that accurately what people are eating. We don’t have a standardized system in the United States for monitoring it. The whole reason a new category—the tolerable upper intake levels (ULs)—was introduced was to address this. I think we need to be a little cautious.

Blumberg: I don’t see anything in the Center for Disease Control’s Morbidity and Mortality weekly report that there is an epidemic of people showing up in emergency rooms with vitamin toxicities. When we look at the RDAs versus the ULs for most nutrients, we are talking about 5 to 10 times higher than that. So there is a pretty big range for most nutrients before you run into the potential for harm. Vitamin A [which has been associated with bone loss] is an exception.

Lichtenstein: I agree. I’m not saying that there is harm. I guess the question I would ask somebody is: Are you already getting the equivalent of a multivitamin supplement in your diet because of your breakfast cereal, because you’re drinking multiples of vitamin waters, because you are choosing fortified OJ?

Mason: This goes back to one of the buzzword phrases we often hear these days: personalized medicine. In many instances health care can be both more effective and less expensive if the care is tailored to each person’s needs. I think another issue we are struggling with here with is the distinction between making public health recommendations for an entire population versus recommendations for a particular individual; failing to distinguish between the two can put us at loggerheads.

Blumberg: One meaningful step toward personalized nutrition is if your doctor would just give you a little dietary assessment.

Mason: I bet you could design a five-item questionnaire that would effectively and validly define those people who could potentially benefit from a multivitamin versus those who wouldn’t. While you’re waiting in the doctor’s waiting room, instead of reading a six-month-old issue of Cosmopolitan, you could just as soon answer the five questions, and the physician assistant would say, “You know what? You fall into a category that would benefit from a multivitamin.”

Lichtenstein: Or the physician assistant would say, “We need to probe more.”

—Adapted, expanded and updated from Tufts Nutrition alumni magazine

Meet the Tufts Experts

– Jeffrey Blumberg, PhD, Friedman School professor and director of the HNRCA Antioxidants Research Laboratory

– Johanna Dwyer, DSc, Tufts Medical School professor, director of the Frances Stern Nutrition Center and a senior nutrition scientist at the HNRCA, and a contractor at the Office of Dietary Supplements, NIH

– Alice H. Lichtenstein, DSc, Gershoff Professor of Nutrition Science and Policy at the Friedman School, professor at Tufts Medical School, director of the HNRCA Cardiovascular Nutrition Laboratory, and executive editor of the Tufts Health & Nutrition Letter

– Joel Mason, MD, professor at the Friedman School and Tufts Medical School and director of the HNRCA Vitamins and Carcinogenesis Laboratory


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